1. Technical Field
The present invention relates to an interactive projector and a system thereof each capable of receiving an instruction of the user to a projection screen with a pointing element.
2. Related Art
JP-A-2012-150636 discloses a projection display device (projector) capable of projecting a projected screen on a screen, and at the same time taking an image, which includes an object such as a finger, with a camera to detect the position of the object using the taken image. The object such as a finger is used as a pointing element for making an instruction to the projected screen. In other words, when the tip of the object is in contact with the screen, the projector recognizes that a predetermined instruction such as drawing is input to the projected screen, and then redraws the projected screen in accordance with the instruction. Therefore, it is possible for the user to input a variety of instructions using the projected screen as a user interface. The projector of the type capable of using the projected screen on the screen as an inputting user interface as described above is referred to as an “interactive projector.” Further, the object used for making an instruction to the projected screen is referred to as a “pointing element.”
In the interactive projector, in order to detect the position of the pointing element, the pointing element is irradiated with detection light such as an infrared ray, and the detection light reflected by the pointing element is imaged by the camera. When detecting the position of the pointing element from the image thus taken, where in the image the pointing element is located is determined using a difference in contrast between the pointing element and the projected screen. Therefore, in the image taken by the camera, it is desired that the difference in contrast between the pointing element and the projected screen is sufficiently high.
However, the inventors of the invention have found out the fact that it is not necessarily easy to sufficiently enlarge the contrast between the pointing element and the projected screen, and in some cases, the contrast cannot sufficiently be obtained depending on the way of applying the detection light.